Method for removing a filter cake from a filtering device

ABSTRACT

A method for removing a filter cake from a filtering device having a housing that defines a filtration flowpath through which a filtrate flows, the housing having at least one inlet and at least one outlet, the filter cake being deposited on at least one cylindrical filter element disposed within the filtering device, the at least one cylindrical filter element comprises at least one filter material and at least one rebound element, the at least one rebound element having a first flange extending from a head region and a second flange extending from a foot region, the at least one rebound element having a structured surface with at least two recesses mutually parallel in the longitudinal direction of the at least one rebound element, the at least two recesses are formed extending between the first flange and the second flange.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 12/430,531, filed on Apr. 27, 2009, which is a continuation ofPCT/EP2007/009123 filed on Oct. 22, 2007, which claims priority toGerman Patent Application DE 10 2006 050 127.6 filed on Oct. 25, 2006,all of which are incorporated herein by reference in the entirety.

FIELD OF THE INVENTION

The present invention relates to a filtering device for cleaningparticularly a liquid and/or gaseous medium as well as to a filterelement that can be inserted in this filtering device and also to amethod for cleaning a medium and to a method for removing a filter cakethat has become deposited in the filtering device according to theinvention.

BACKGROUND OF THE INVENTION

Many different filtering devices for cleaning liquid and/or gaseousmedia or corresponding mixtures, including also high-viscosity and oilymedia, are known from the state of the art. A particularly problematicaspect of the filtering devices that are known from the state of the artis the removal of the filter cake that becomes deposited on a filterelement contained in the device, or mud collected there. On thissubject, U.S. Pat. No. 7,055,699 B2 proposes a self cleaning mechanicalfilter, where a cleaning device is integrated in the filtering devicedisclosed there and presents suction and washing nozzles that arearranged opposite each other, and where the suction nozzles restdirectly against the filter element, and the suction nozzles and thewashing nozzles are moved synchronously in the axial and radialdirection for removal of the filter cake. The cleaning of the filteringdevice that is disclosed in U.S. Pat. No. 7,055,699 B2 is verycomplicated and requires complex control. In addition, because of themovement in both the axial and also the radial direction, a relativelyhigh mechanical driving force needs to be applied, which makes thefiltering device disclosed there relatively costly.

Moreover, a filtering device according to the preamble is disclosed inWO 2006/008729, where, for the removal of a filter cake on a filterelement in a filtering device, a cleaning head with a nozzle is definedparticularly, which rests directly against the filter element, andthrough which, due to a pressure difference that builds up during thecleaning, the filter cake is sucked off the filter element. For thefiltering device that is disclosed there to work properly, it is,however, always necessary to guide the cleaning head of the cleaningdevice so that it rests directly against the filter element, with theresult that the pressure difference that can be generated for cleaningis insufficient in the case of slight unevenness that developsparticularly in the filter elements or their surfaces in the case ofprolonged use of the filtering device.

The problem of the present invention therefore is to make available afiltering device whose filter material or whose filter element(s) can becleaned particularly well and simply due to the construction of thedevice, and which in addition effectively cleans a medium to be cleaned,regardless of whether the latter is gaseous, liquid or a mixture thatmay be of any type.

SUMMARY OF THE INVENTION

This problem is solved by a filtering device with a housing with atleast one filter element arranged in it, comprising at least one filtermaterial and at least one rebound element, and with a cleaning device,comprising at least one nozzle, which can be directed, for the removalof a filter cake, on the filter material by means of a cleaning mediumperpendicularly and/or angularly in relation to the filter element,where, for the cleaning, the cleaning medium at least partiallypenetrates the filter material, and the rebound element deflects thecleaning medium at least partially for the renewed passage through thefilter material, with at least partial removal of the filter cake at thesame time. Advantageously, exactly one nozzle or nozzle block isassociated with one filter element.

The filtering device according to the invention presents the greatadvantage that, due to the specific design of the filter element with atleast one rebound element, a very effective removal of the filter cakethat is being deposited on at least one filter material occurs, wheresuction nozzles that are known from the state of the art mentioned inthe introduction are provided at the same time. The filtering deviceaccording to the invention can therefore be manufactured considerablymore cost effectively, while the same good cleaning performance isachieved and also a more effective removal of the filter cake. Due tothe feeding of the cleaning medium through the at least one nozzleperpendicularly and/or angularly in relation to the filter element, anindividual and effective removal of the filter cake can occur, which isadapted to the specific properties of the medium to be cleaned, andtakes into account the overall construction of the filtering device. Theat least one nozzle can here be designed particularly so it is alsomovable and/or individually controllable. It is preferable for thecleaning device to present at least one nozzle row or else a nozzlefield. Each of the individual nozzles of such a nozzle row or nozzlefield design can here be designed to be movable, and it can becontrolled separately; however, any desired combinations including fixednozzles or consisting exclusively of fixed nozzles are conceivable.Here, the nozzles are directed perpendicularly on the filter element,the cleaning medium impacts perpendicularly on at least one filtermaterial of the filter element, penetrating through the latter, wheresubsequently the cleaning medium is then reflected by the surface of therebound element by approximately 180 degrees, as a function of thefilter material used and its deflection of the cleaning medium as wellas of the surface of the rebound element, where subsequently thecleaning medium then again penetrates through the filter material,clearing the filter cake at least partially or rinsing mud at leastpartially out of the filter element.

In an alternative embodiment for this, the nozzles are oriented at anangle of preferably approximately 5 to approximately 85 degrees, inrelation to the filter element or its surface, so that the cleaningmedium impacts the filter material of the filter element at acorresponding angle, penetrates through the filter material, and then isreflected from the surface of the rebound element at an angle thatcorresponds more or less to the rebound angle, as a function of thefilter material used. The cleaning medium that has been reflected inthis way again penetrates through the filter material, and it removesthe mud or filter cake, which has been collected up or has deposited onor in the filter material of the filter element. Such an angulararrangement of the nozzles with respect to the surface of the filterelement is particularly advantageous when the cleaning device isdesigned to be movable in a preferred embodiment, so that, in thedirection of movement, the cleaning medium can be fed on the filterelement and the filter material angularly, which results particularly infacilitating, particularly in accelerating, the removal from thefiltering device of the cleaning medium that has become contaminatedwith the protection [sic; mud] or filter cake.

In another alternative embodiment, the cleaning device can also presentnozzles that are oriented both vertically and angularly in relation tothe surface of a filter element, where, for example, in an arrangementin the form of a nozzle row, first a nozzle row can also be providedthat feeds the cleaning material perpendicularly on the filter element,and subsequently a nozzle row that discharges the cleaning medium on thefilter element angularly in relation to the surface of the filterelement, and particularly in the direction of movement in the case of amovable cleaning device. Naturally, the reverse arrangement is alsoconceivable. All possible combinations of arrangements of nozzles in thecleaning device as well as their orientation in view of the filterelement are in accordance with the invention.

The cleaning medium is released out of the nozzles of the cleaningdevice, preferably under pressure, here preferably at a pressure of morethan 3 bar, and more preferably at a pressure of more than 5 bar. As aresult, the cleaning effect is increased, and the cleaning step isaccelerated.

It is preferable for the filter element of the filtering device topresent a cylindrical and/or flat design. Here, the cleaning device canpresent particularly several, i.e., at least two filter elements withcylindrical and/or flat design. Flat filter elements can be arrangedhere particularly in one or more rows, while cylindrical filter elementscan be accommodated preferably as an individual piece or in groups oftwo, three or four, or in groups of a multiple of the above-mentionedgroups, in a filtering device. It is advantageous here for a nozzle, ora nozzle block to be associated with a filter element of cylindricaldesign, where it is preferable furthermore for the filter element to bedesigned so it can be moved. Flat pursuant to the present inventionmeans that the filter elements can be designed, for example, as flatcuboids, which may be square or rectangular. Any other design of thefilter element pursuant to the present invention is, however, alsopossible.

A partial area of a surface of the filter element can serve as a reboundelement. This rebound element of the filter element of the filteringdevice can be designed as a rebound metal plate, particularly onepresenting any conceivable shape that is adapted to the circumstances,for example, quadrangular, cylindrical or also spherical. The reboundelement can here present openings for the passage of the cleanedfiltrate. For example, a construction is conceivable in which the filterelement presents a filter material, for example, nonwoven or yarn, whichis pulled onto a simple frame structure, where, behind this filtermaterial, the rebound element in the form of a metal plate is arranged.Such an arrangement can also occur spherically, for example, where therebound element then comes to lie in the interior, or else outside thesphere defined by the filter element, where a cleaning of a medium to becleaned can then occur from the inside toward the outside, or from theoutside toward the inside, depending on the arrangement of the filtermaterial and of the rebound element. If the filter material itselfpresents sufficient stiffness and rigidity, then a frame structure thatcarries the filter material and confers its shape to the latter can alsobe omitted. This can be the case, for example, when using sintered metalbodies as filter material.

Pursuant to the present invention, it is also possible to provideseveral rebound elements next to each other, one after the other, orpartially overlapping. It is particularly preferable for the reboundelement to be formed by a filter housing, which is at least partiallyenclosed or arranged partially with the at least one filter material.The filter housing itself can present, particularly in a head areaand/or foot area of the same, outlets that are arranged for releasingthe cleaned filtrate, flanges for the attachment in the interior of afiltering device to achieve a reliable securing in the latter, as wellas other needed means and elements. For example, the rebound element canbe formed by a flat solid block, particularly one made of a metal and/orplastic material, or of an at least partially hollow cylinder, where theflat block or else the cylinder can be open at one or else at both endsfor the discharge of the cleaned filtrate. On the upper surface or theperipheral surface of the block or the cylinder, the filter material isthen arranged, at least in partial areas of said surface. Moreover, inthe filter housing that is formed from the block or cylinder, at leastone opening is provided, through which the filtrate can enter into theinterior and be released from the filtering device according to theinvention through outlets that are associated with the head areas or thefoot areas.

It is particularly preferable for the surface of the rebound element topresent an at least partially structured design. By structuring thesurface of the rebound element, advantageously, on the one hand, asimplified and particularly also accelerated outflow of the cleanedfiltrate is achieved, particularly also in a directed way, towardopenings that are provided on the filter element, and, moreover, duringthe cleaning of the filtering device, the cleaning medium that impactsunder pressure is also reflected or scattered at different angles,resulting in an increase in the cleaning effect. The structure of thesurface of the rebound element can be of any conceivable design; forexample, the surface can be simply embossed in the shape of a point orline, or its design can be wavy, for example. It is preferable for thesurface to present a structure that is formed from at least two recessesthat run parallel to each other, viewed in the direction of alongitudinal axis L of the rebound element. Between the recesses, it ispreferable to arrange particularly rib-shaped embossments. Theembossments, if of linear design, can also present gaps, so that themedium to be cleaned can move from one recess to the adjacent recess.The gaps can be offset with respect to adjacent embossments or arrangedwithout offset. In particular, embossments can also be arranged in sucha way on the surface of the rebound element that continuous linear,particularly rib-shaped, embossments alternate with embossmentsinterrupted with gaps. The filter material is in contact with theembossments, so that the filtrate can be led through the recesses toopenings, and be released. The recesses are designed preferably asgrooves, which end shortly before or at the head area and/or foot areaof the rebound element, particularly in the case of a design as a filterhousing. The grooves can here present a uniform depth or a varying depthover their entire length; for example, they may also present an inclineparticularly toward an opening. In the recesses, openings can beprovided, preferably at least two for each recess.

In an additional preferred embodiment, the surface structure of therebound element presents at least one recess that runs diagonally to thelongitudinal axis L, and which is also designed preferably as a groove.Here, recesses that run diagonally can also be combined with recessesthat run parallel. The recesses are here preferably distributeduniformly over the entire surface of the rebound element that is coveredwith the filter material. If only a part of the rebound element isenclosed with a filter material, corresponding structures need to beapplied only in the area of the application of the filter material.

In a flat or block-like design of the rebound element in the form of afilter housing, it is preferable here for the at least one recess thatis arranged diagonally to the longitudinal axis L to end in theimmediate vicinity or in the head area and/or foot area of the filterhousing. The opposite end of the corresponding diagonally runningrecesses can here end in a longitudinal side of the flat, block-likefilter housing. Accordingly, the diagonally running recesses can bearranged on a cylindrically designed filter body. The diagonally runningrecesses can here present a rectilinear design, but they can alsopresent a radial, for example, quadrant, shape. However, any otherdesign of the recess that runs at least in partial areas diagonally,i.e., angularly, in relation to the longitudinal axis L, is advantageouspursuant to the present invention. If the diagonally running recessesend in the vicinity or in the head area and/or foot area of the reboundelement, openings should preferably be provided there for the passage ofthe cleaned filtrate, because here, due to the specific surfacestructure of the rebound element, the filtrate is transported throughthe recesses on the opening(s). The openings can be point-shaped,circular, slit-shaped, or of any other design. It is also possible inparticular to arrange openings that are also distributed over theremaining surface of the rebound element, particularly in the recessesof the surface of the rebound element.

Depending on the design of the rebound element, the latter can presentan at least partially structured surface on one side, or also on bothsides. In a flat, block-like design or a cylindrical design of therebound element, particularly as a part of a filter housing, it ispreferable to provide the entire surface in a cylindrically designedrebound element, or both sides in a flat, block-like rebound element,with a surface structure in the area of the adjacent filter material.

The filter material is chosen preferably from a group comprisingnonwovens, fibers, fabrics, yarns and/or sintered metal bodies. Here itis also particularly possible to provide combinations of differentfilter materials, including for the generation of a filtration gradientin the filter element. In particular, sintered metal bodies with anintegrated gradient pattern and manufactured from mixtures of sinteredmetal powders and sintered metal fibers, including with inserted fabricstructures, etc., can also be used. It is preferable, pursuant to thepresent invention, to use as filter material a yarn that consists of oneor more fine/thin individual filaments. It is preferable to use at leasta yarn as filter material, because, during the filtration and cleaningprocess, the yarns vibrate, and as a result they support the filtration,on the one hand, and also the cleaning due to a facilitated removal ofthe filter cake. The yarn preferably presents a textured design, whichallows considerably more soiling particles to be caught. It ispreferable for the individual elements of the yarn to present a diameterof up to approximately 1 mm, preferably up to approximately 0.5 mm, andeven more preferably approximately to 0.01 mm. The yarn as well as otherfilter materials are used here preferably in at least two, and morepreferably in more than two, layers. In this way, very fine filtratescan be obtained, regardless of whether they are gaseous or liquid. Thecleaning device according to the invention connects the mode ofoperation of an edge cleaning filter with that of a depth filter.

It is preferable for the cleaning device to present a sled-type design.The cleaning process comprises the at least one nozzle, which isarranged preferably on a nozzle block. In this nozzle block, severalnozzles can be arranged, including particularly together in a nozzlerow, and also as a nozzle field. A sled-type design of the cleaningdevice is advantageous particularly in a flat design of the filterelement for the filtering device. Otherwise the cleaning device can alsocomprise a cylindrically designed nozzle block with nozzles arranged onit. The cleaning device can be driven here preferably hydraulically,electrically or mechanically, or via a gearing, for example, a wormgear. Alternatively, one can also provide for the cleaning device topresent a stationary design, and the filter elements are moved. This isparticularly advantageous with a cylindrical design of the filterelements. It is preferable to associate at least one nozzle with eachindividual filter element housed in the housing. As a result, thecleaning performance can be increased further. Here it is particularlyadvantageous, in the case of flat filter elements, for a nozzle block,particularly one with a nozzle row, to be associated with each side ofthe filter element that is provided with the filter material.Alternatively, the nozzle blocks can also present, in the case of filterelements that are arranged in several rows next to each other or inanother arrangement, several nozzles that point in different directions,for the purpose particularly of cleaning several filter elements at thesame time. In a flat filter element with filter material arranged onboth sides, facing nozzle blocks, which extend over the entirelongitudinal direction of the filter material, can be associated withone or more filter elements, particularly in the case of filter elementsarranged in several rows, and, during the cleaning of the filterelement(s) for removing the filter cake or the mud, they can be moved onor in them over the entire surface of one or more filter elements. Onecan also provide for at least two filter elements to be associated withat least one nozzle. This may be the case, for example, if the nozzleblock with the at least one nozzle has a design that allows rotation,particularly in the case of the use of cylindrical filter elements, orif the filter elements themselves present a design that allows rotation.

If the filter element presents a cylindrical design, then it ispreferable for the filter elements to be movable, and for the cleaningdevice in the form of a cylindrical nozzle block with arranged nozzle tobe stationary, where the latter device can also present a design thatallows rotation. For example, if four filter elements in a group arearranged together on an approximately square base area, then acylindrically designed nozzle block can be arranged in the middlebetween them and present a respective nozzle row that is directed ontoeach of the four filter elements. By the rotation of the filterelements, for example, via a gearing, particularly a worm gear that isarranged in an outlet area, it is alternatively also possible to achievein this way a cleaning of the entire surface of the filter material of acylindrically designed filter element by pressurized air orhydraulically, for example, in the case of a stationary, cylindricalnozzle block. However, the nozzle block may also present only one nozzlerow, and a design that allows rotation.

At least one opening in filter elements with cylindrical or flat designcan be arranged at each position of the surface of the area that iscovered with filter material, particularly also on a head area and/orfoot area of the rebound element that is covered with filter material.The openings can present a design of any possible shape, for example, around or an angular opening cross section, slit-shaped, etc.

The present invention relates moreover to a filter element thatcomprises at least one rebound element and at least one filter material,where the rebound element presents an at least partially structuredsurface. For the rest, the filter element according to the inventionpresents the advantageous embodiments that have already been representedabove, particularly concerning the surface structure.

Moreover, the invention relates to a method for cleaning of aparticularly gas and/or fluid medium, particularly in industrialinstallations, where the medium is cleaned at least partially by atleast one filter element according to the invention with an at leastpartially structured surface on the rebound element of the same.

Finally, the present invention relates to a method for the removal of afilter cake that has become deposited or mud that has collected on atleast one filter element, comprising at least one filter material and atleast one rebound element in a filtering device, where, over at leastone nozzle of a cleaning device, a cleaning medium is directedperpendicularly and/or angularly, in relation to a surface of therebound element, on the filter element, the cleaning medium penetratesthrough the at least one filter material, rebounds at least partially onthe rebound element, and, at the time of a renewed passage through thefilter material, removes the filter cake at least partially. The termsfilter cake and/or mud that becomes deposited on or in the filterelement are synonymous terms pursuant to the present invention.

It is preferable for the cleaning device to be moved during the releaseof the cleaning medium; in an alternative embodiment, at the time of therelease of the cleaning medium, the at least one filter element ismoved. However, combinations of these two designs are also possible. Thecleaning medium is here preferably a liquid and/or gaseous medium, andit can represent particularly also mixtures of liquid, gaseous or liquidand gaseous media. Here, the cleaning medium is chosen in view of theproperties of the medium to be cleaned. It can be, for example, water,pressurized air, oxygen, ammonia, an aliphatic hydrocarbon or else ahydrocarbon mixture, gasoline or a similar substance. However, thepreliminary and post cleaning medium is also chosen in view of thecircumstances. In the case of the cleaning of a gaseous mixture by thefiltering device, it is preferable to use a liquid cleaning medium,which rinses the filter cake/mud out of the filter material. In the caseof the filtration of the liquid medium with the filtering deviceaccording to the invention, it is preferable to use the cleaned mediumitself as cleaning medium.

Before feeding the cleaning medium, it is advantageous to rinse out theremaining medium to be cleaned that is still present in the housing ofthe filtering device with a preliminary cleaning medium. The preliminarycleaning medium can here be fed via an advantageously separate feed ofthe filtering device, and it can be released through an outlet throughwhich the cleaning medium as well flows out of the filtering device. Itcan also be fed particularly advantageously under pressure into thefiltering device, where, in the inlet, a valve is then providedadvantageously, through which the pressure of the fed cleaning mediumcan be controlled precisely. Corresponding valves can also be providedat the inlet of the cleaning medium, and also of the medium to becleaned, which can also be fed under pressure into the filtering deviceaccording to the invention. Similarly, the outlets for the cleanedfiltrate and/or the cleaning or preliminary cleaning medium can also beprovided with a preferably controllable valve. However, any other typesof shutoff devices, for example, ball cocks or similar parts, are alsoconceivable. Due to the additional step of the feeding of a preliminarycleaning medium, the subsequent cleaning with the cleaning medium isadvantageously temporally shortened. Moreover, it is advantageous torinse out any remaining to cleaning medium [sic; medium to be cleaned]that is still present in the housing of the filtering device by means ofa post cleaning medium. The feeding can here occur analogously to thefeeding for the preliminary cleaning medium; however, additional feedscan also be provided. The preliminary and/or post cleaning medium can bein liquid or gaseous form, preferably gaseous, and here it may alsorepresent a mixture of different gases.

When using a yarn-shaped or other material that is oriented in apreferential orientation, it is advantageous to apply the cleaningmedium parallel to the winding or drawing direction of the filtermaterial. This results in a highly efficient cleaning of the filteringdevice according to the invention.

The rebound effect and/or outflow of the cleaning medium is increasedadvantageously by the rebound element by structuring the surface of thelatter. On this subject, reference is made to the explanations givenabove. The structured surface of the rebound element thus allows afacilitated and more rapid outflow of not only the cleaned filtrate butalso of the cleaning medium and/or the preliminary cleaning medium.

BRIEF DESCRIPTION OF THE DRAWINGS

These and additional advantages of the present invention are explainedin further detail below in reference to the following figures.

FIG. 1 a: a perspective view of a filtering device according to theinvention;

FIG. 1 b: a side view of a head side of the filtering device accordingto FIG. 1 a with partial sections;

FIG. 2: a partially broken open perspective view of the filtering deviceaccording to FIG. 1 a;

FIG. 3: an additional broken open perspective view of the filteringdevice according to FIG. 1 a;

FIG. 4: a perspective view of a filter element without filter material;

FIG. 5: a perspective, partially broken open view of a filter elementaccording to the invention with filter material;

FIG. 6 a: a partially broken open perspective view of the filteringdevice according to FIG. 1 a in a starting cleaning position;

FIG. 6 b: a view of the head side of the partially broken open filteringdevice according to FIG. 6 a;

FIG. 7: the cleaning device according to FIG. 1 a in a partially brokenopen view in a middle cleaning position;

FIG. 8: the filtering device according to FIG. 1 a in a partially brokenopen view in an end cleaning position;

FIG. 9: an alternative embodiment of the filtering device according tothe invention;

FIG. 10 a: a cylindrically designed filter element according to theinvention without filter material;

FIG. 10 b: an alternative embodiment of a cylindrically designed filterelement without filter material;

FIG. 11: the filter element according to FIG. 10 a, partially enclosedwith filter material;

FIG. 12: a cylindrically designed filter element in a cross-sectionalview without filter material;

FIG. 13: a partially broken open perspective view of the filteringdevice according to FIG. 9 for explanation of the filtering process;

FIG. 14: a partially broken open view of the filtering device accordingto FIG. 9 for illustrating preliminary cleaning; and

FIG. 15: the [sic] a partially broken open view of the filtering deviceaccording to FIG. 9 for facilitating cleaning of the same.

DETAILED DESCRIPTION OF THE INVENTION

First, it must be stated beforehand that the characteristics shown inthe figures are not limited to the individual embodiment. Rather, thecharacteristics that are indicated in each case in the description,including the description of the figures, and the drawing, can becombined to produce variants. In particular, the object of the presentinvention is not limited to the number of filter elements that arearranged in a housing in the filtering device according to theinvention, or else with regard to the arrangement of the openings forthe passage of the cleaned filtrate into the filter elements.

FIG. 1 a shows a filtering device according to the invention, whichoverall bears a reference character 10, with a housing 12, whichpresents an approximately cuboid-shaped design. This housing 12 presentsan inlet 24 with a valve V1 for the feeding of a medium to be cleanedand corresponding outlets 26.1 and 26.2 with valves V2 and V3 that areassociated with them. Moreover, the filtering device 10 presents aninlet 28 with a valve V6 that is associated with it, and serves for theintroduction of a preliminary cleaning medium, and a correspondingassociated outlet 30 with a valve V4 that is associated with it.Finally, via a feed 32 and a valve V5 that is associated with it, acleaning medium is fed into the filtering device via the feed lines 34.1and 34.2 of the filter, where this cleaning medium can be releasedthrough the outlet 30 out of the housing 12 of the filtering device 10.Moreover, in FIG. 1 a, a pressure sensor 38 can be seen, which isconnected to a filtrate receiving element 40.1. The filtrate receivingelement 40.1 is arranged on a longitudinal side of the housing 12 of thefiltering device 10, and correspondingly with the former element, anadditional filtrate receiving element 40.2 is arranged on the oppositelongitudinal side of the housing 12. These filtrate receiving elements40 are connected to the filter element, which is not represented in FIG.1 a, in the interior of the housing 12, and they present a channel, notrepresented here, in which the pressure sensor 38 engages.

This construction of the filtrate receiving elements 40.1 and 40.2 canbe seen particularly in FIG. 1 b. There, the arrangement of a filterelement 14 with outlets 44 on its two front sides can be seen. Thefilter element 14 here presents a flat and block-like design. Theoutlets 44 end in the filtrate channels 42.1 and 42.2 that are arrangedin the filtrate receiving elements 40.1 and 40.2. Moreover, in FIG. 1 b,an additional pressure sensor 36 can be seen, which measures thepressure of a medium to be cleaned that flows into the housing 12 and isfed via the feed 24. By measuring the pressure difference between thepressure sensors 36 and 38 in case of soiling of the filter element 14,and in the case where a predetermined target value is reached, the feedof the medium to be cleaned is stopped by the valve V 1, and then thecleaning process, which is explained below, can be started. The cleaningprocess can in principle also be started at any time with/withoutexisting pressure difference pursuant to the present invention.

FIG. 2 shows a partially broken open perspective view of the filteringdevice 10 according to FIG. 1 a, where one can see clearly that thearrangement of a total of five filter elements 14.1, 14.2, 14.3, 14.4and 14.5 in a row also comprises the design of a cleaning device 20,which comprises the feed line 32, the valve V5, the feed lines 34.1 and34.2 for the cleaning agent as well as the nozzle blocks 68.1, 68.2,68.3, 68.4 and 68.5 that are arranged on the feed line 34.1. Thesenozzle blocks are arranged correspondingly on the opposite side of thefilter elements 14.1-14.5 on the feed line 34.2. The nozzle blocks 68thus present a paired arrangement and association in each case with onepredetermined filter element 14. Thereby, the nozzle block 68 can alsopresent, for example, in the case of filter elements 14 that arearranged in rows next to each other, nozzles oriented in severaldirections, so that a nozzle block can clean several filter elements atthe same time. The filter elements 14.1-14.5 are enclosed here on bothsides with a filter material, preferably a textured yarn consisting ofone or more very thin individual filaments, preferably in severallayers.

FIG. 2 shows the feed of the medium 58 to be cleaned, indicated byseveral black arrows, via the feed 24 and the valve V1 into the interiorof the housing 12 of the filtering device 10. The medium 58 to becleaned here penetrates into the filter elements 14.1 and 14.5 throughthe filter material that is arranged on the elements, and, in the end,it is led via the channels 42.1 and 42.2, which are arranged in thefilter receiving elements 40.1 and 40.2, to the outlets 26.1 and 26.2,from which the cleaned filtrate 60 is then removed from the filteringdevice 10.

The paired arrangement of these blocks 68 can be seen in greater detailin FIG. 3, where the arrangement will be described in greater detailhere with a view to the filter element 14.5 and the nozzle block pair68.5. The filter elements 14.1-14.4 or the nozzle block pairs 68.1-68.4present corresponding designs. FIG. 3 is the arrangement of a nozzle row22 with a plurality of fixed and/or movable nozzles, which release thecleaning medium perpendicularly or angularly in relation to the filterelement 14. The blocks 68.5 present a cuboid-shaped design, and theyextend in their longitudinal direction over the entire surface of thearea of the filter element 14.5 that is enclosed with a filter material.

FIG. 4 shows an individual filter element 14, without filter material,the like of which is accommodated five times in the filtering deviceaccording to FIG. 1 a. The filter element 14 presents, in a head area 54and a head [sic; foot] area 56, which present a flange-shaped design,three arranged outlets 44 in each case, through which cleaned filtrateis led to the channels 40.1 [sic; 42.1] and 40.2 [sic; 42.2], which arearranged in the filter receiving elements 40.1 and 40.2. The surfaces46.1 of the front side and 46.2 of the back side of the flat, block-likefilter elements 14 according to FIG. 4 present a structure where on saidsurfaces in each case a plurality of longitudinal recesses 48,presenting a groove design, is arranged, so that they run parallel toeach other, and are intersected by diagonally running recesses 50. Thesediagonally running recesses 50 here are arranged in a rhombic patternover the entire surface of the filter area 14 that is covered with afilter material, and accordingly they intersect the recesses 48 that runin parallel. The recesses 48 and 50 terminate in each case in the headarea 54 or the foot area 56. The head area 54 and the foot area 56present in each case a slit-shape opening 52, not shown in greaterdetail in FIG. 4, which extends over the entire width of the filterelement 14, for receiving the cleaned filtrate that is fed through thestructured surface via the recesses 48 and 50 of these slit-shapedopenings 52. The rebound element 18 of the filter element 14 here isdesigned as a solid filter-housing body; in the flange-shaped design ofthe head area 54 and of the foot area 56, corresponding hollow cavitiesor channels are provided, through which the cleaned filtrate is led tothe outlets 44. However, the opening 52 can also present any other typeof design, in particular, several openings 52 can also be distributedover the entire surface of the rebound element 18. The openings 52 canbe provided particularly in the recesses 48 and 50, where the reboundelement 58 then presents a design that is hollow or else is providedwith channels, so that the filtrate 60 that has been received throughthese openings can be led to the outlets 44.

FIG. 5 now shows the mode of operation of the filter element 14, wherein said figure the filter material 16 is also clearly visible in apartially broken open view. The latter material is designed as a fibrousyarn, and encloses the solid body of the rebound element 18. The mediumto be cleaned 58, as illustrated by arrows that impact the filterelement 14 from the outside) [sic], flows through the filter material 16on the filter element 14, where the cleaned filtrate 60 that isillustrated by small arrows, is then led via the recesses 48 and 50 onthe surface 46.1, and also on the surface 46.2 facing the formersurface, to openings 52 that are arranged in the head area 54 and thefoot area 56. The filtrate 60 that has thus been deflected by thesurface 46.1 or 46.2 of the rebound element 18 leaves the filter element14 through the outlets 44.

The functioning of the cleaning step of the filtering device 10according to the invention is explained in greater detail in referenceto FIGS. 6-9. FIG. 6 a here shows a partially broken open view of thefiltering device 10 according to FIG. 1 a, where the cleaning device 20is arranged in a starting position. The valves V1, V2, V3 and V6 areclosed, and the valves V4 and V5 are opened. In FIG. 6 a, the nozzle row22 of the nozzle block 68 can be seen clearly, which is associated onthe feed lines 34.1 and 34.2 in pairs with each filter element 14. Thecleaning device 20 is designed as a sled, and it is movable in thedirection of an arrow 78, but naturally also in the opposite directionto reach the starting position. The blocks 68 are, with respect to eachone of the total five filter elements, in a starting position slightlyin front of the longitudinal side of the filter element 14. The cleaningmedium 62 is led through the feed 32, which is regulated by the valveV5, to the filtering device 10. In this position, the valves V1-V3,which are open in the filter process proper, have to be closed, and thesame applies to the valve V6 that serves for feeding the preliminarycleaning medium. Only the valves V5 and V4 are open. The cleaning medium62 that is mixed with mud/filter cake flows out of the housing 12 of thefiltering device 10 via the valve V4 and the outlet 30. FIG. 6 b shows,in a side view, the construction and the position of the cleaning device20 according to FIG. 6 a, and also the arrangement of the pressuresensors 36 and 38 as well as the construction of the filtrate receivingelements 40.

FIG. 7 now shows the cleaning device 20, which is moved in the directionof the arrow 78, in a middle position, in which the nozzle blocks 68that are arranged in both sides of the filter body 14 have reachedapproximately the middle of the filter element 14 at the height of themiddle outlet 44.

In FIG. 8 one can see the end position of the cleaning device 20, inwhich the nozzle blocks 68 are finally moved over the entire lateralsurface of the filter element 14, and assume their end position betweenthe adjacent filter elements 14. All the cleaning medium 62 is removedthrough the outlet 30 of the filtering device 10. Optionally,preliminary cleaning medium, particularly gaseous preliminary cleaningmedium, can be fed again via the valve V6 to the filtering device 10, toremove residues of the cleaning medium 62 from the filtering device 10.The cleaning device 20 could naturally also be designed so that only onenozzle block pair 68 is provided, which moves over all five filterelements 14 arranged in a row. However, as a result of the assignment ofa total of five nozzle block pairs 68 to each filter element 14, aconsiderable acceleration of the cleaning is achieved. After thecompletion of the cleaning, the cleaning device 20 is moved again intothe starting position according to FIG. 6 a.

FIG. 9 now shows an alternative embodiment of the filtering device 10according to the invention, which, in contrast to the one shown in FIG.1 a, does not present flat filter elements 14, but rather, as shown inFIGS. 10-15, presents cylindrically designed filter elements. As anotherdifference compared to the filtering device shown in FIG. 1, thealternative embodiment shown in FIG. 9 presents only one outlet 26,which is provided with a valve V2, for the filtrate to be cleaned. Viathe feed 32 and the valve V3 that is associated with it, cleaning mediumcan be fed to the device 10, and via the outlet 30 and the valve V4 thatis associated with it, it can be removed. Through the inlet 28 and thevalve V5 that is associated with it, preliminary cleaning medium can befed to the device 10. Finally, in contrast with the filtering deviceaccording to FIG. 1 a, the alternative embodiment shown in FIG. 9presents a junction element 74, in which the cleaned filtrate to beremoved from the total of four cylindrical filter elements 14 (see FIGS.10-15) is united, and led to the outlet 26. However, each cylindricalfilter element chosen can also be associated with its own outlet 26.

In FIG. 10 a, the construction of the cylindrically designed filterelement 14 shown without filter material can be seen. They presentrecesses 48 that are parallel and run in the longitudinal direction ofthe filter element 14 over the entire peripheral surface of the area ofthe filter element 14 that is to be covered with filter material, where,in the recesses 48, circular or angular openings 52 are arranged in theshape of a circle along the periphery of the cylindrical filter element14, through which openings cleaned filtrate can enter into the interiorof the cylindrical filter element 14. Alternatively, one could provide,for example, openings 52 on each end of the grooves 48 in question inthe head area and/or foot area 54 or 56. A head area 54 presents aflange 72.1, and a foot area 56 presents a flange 72.2, by means ofwhich the cylindrical filter element 14 is securely attachable in thedevice 10 according to FIG. 9. Moreover, the filter element 14 presentsan outlet 44 for the cleaned filtrate.

FIG. 10 b shows an alternative embodiment of a cylindrically designedfilter element 14 with respect to that shown in FIG. 10 a, which againis represented here without filter material. The filter element 14 herepresents particularly in addition a worm gear 45, through which thecylindrically designed filter element 14, during use, can be movedrotatably in a filtering device 10, as shown, for example, in FIG. 9, bymeans of appropriate engaging gear wheels, which are not shown.Moreover, a partial area of a surface 46 of the filter element 14presents a structuring with recesses 48 and, between the latter,rib-shaped embossments 49 are arranged. The recesses 48 are heredesigned so that they start from a flange 72.1 in a head area 54 of thefilter element 14 and run linearly to a second flange 72.2 in a footarea 56, and similarly the corresponding embossments 49. The embossments49 are designed here in such a way that alternately embossments 49 arearranged that present gaps 47, in FIG. 10 b, for example, three offsetgaps 47 for each embossment 49 or four gaps 47 for each embossment 49,over the entire length between the flange 72.1 and 72.2. By means ofthese gaps 47, the filtrate can be led between adjacently arrangedgroove-shaped recesses 48. In the recesses 48, openings 52 are providedfor the passage of the filtrate 52 [sic; 60] into the interior of thefilter element 14. In the process, several, for example, six or aplurality of such openings 52 can be distributed over the entire area ofthe structured surface 46 in recesses 48. The openings 52 can also bearranged in the head area (flange 72.1) and/or the foot area (flange72.2), for example, in the area of an extension of at least one recess48.

FIG. 11 shows the filter element according to FIG. 10 a, now enclosedpartially with a filter material 16 in the form of a textured yarn.Here, the arrows 58 illustrate the feeding of a medium to be cleaned,which penetrates through the filter material 16, and which is fedcleaned, as filtrate 60, illustrated by the arrows 60, through therecesses 48 to the openings 52, and finally it leaves the cylindricalfilter element 14 via the opening of the outlet 44.

The filter element 14 according to FIGS. 10 a and 11 is here designed tobe open on one side. However, it is also entirely possible for thecylindrically designed filter element to present two outlets 44, whichare arranged on the opposite head areas 54 and foot areas 56, so thatthe cleaned filtrate 60 can leave the filter element 14 on both frontsides.

FIG. 12 shows the cylindrical filter element 14 according to FIGS. 10 aand 11 in a cross-sectional view, where the openings 52 with theirassociated opening channels 70 can be seen particularly clearly. Therebound element 18 here consists of a hollow body formed from a metaland/or plastic material. In the foot area 56, the filter element 14 isclosed, and, on the head area, 54, the outlet 44 is arranged connectedto the flange 72.1 located there.

FIGS. 13-15 now show the individual filtration, preliminary cleaning andcleaning steps, where the filtration step and the preliminary cleaningstep are carried out accordingly with the device shown in FIG. 1 a. Themedium to be cleaned 58 passes through the inlet 24, which is regulatedby the valve V1, into the interior of the filtering device 10, itpenetrates through the filter material of the total of four filterelements 14 that are arranged so they face each other in anapproximately square base area, is transferred via the openings 52,which are not shown in greater detail in FIG. 13 (see FIGS. 10-12), ascleaned filtrate, into the interior of the filter elements 14, thefiltrate 60 is finally cleaned in the joining element 74, and is removedthrough the common outlet 26 following the valve V2 of the device 10. Ifthe pressure difference that is measured by the pressure sensors 36 and38 now becomes so large that a predetermined target value is exceeded,the valves V1 and V2 are closed, and the preliminary cleaning orcleaning of the device 10 is set in motion; however, the process canalso be started at any time with/without existing pressure difference.Naturally, it is also possible to provide more than or fewer than fourfilter elements 14.

FIG. 14 shows the preliminary cleaning step, where a preliminarycleaning medium 64 is fed via the feed 28, which is regulated by thevalve V5, to the device 10, while being preferably gaseous and underpressure, which results in any filtrate 60 or medium to be cleaned 58that is still present in the interior of the device 10 being releasedvia the outlet 64 [sic; 44], which is regulated by the valve V4, out ofthe device 10. After a predetermined time period, the feed of thepreliminary cleaning medium 64 is then interrupted by closing the valveV5, and the cleaning proper is set in motion.

FIG. 15 shows the cleaning of the device 10, where the cleaning medium62 is fed via the feed 32, which is regulated by the valve V3, to anozzle block 68 with nozzle rows 22. The nozzle block 68 here presents acylindrical design, and it presents at least one nozzle row 22associated or corresponds with each of the four filter elements 14,i.e., a total of at least four. The individual nozzles of the nozzle row22 can here apply the cleaning medium 62 perpendicularly and/orangularly on the surface of the filter element 14. The cleaning element62 penetrates through the filter material 16 which at least partiallycovers the rebound element 18, it penetrates again through the filtermaterial 16 of the filter elements 14, and it is subsequently removedagain via the outlet 30, which is regulated via the valve V4, out of thedevice 10. Here, one provides for the nozzle block 68 to present astationary design, and for the filter elements 14 to be movable, whichis illustrated by the arrow 76. The filter elements 14 here rotate abouttheir main axis, so that the total surface of the filter elements 14 canbe imbued uniformly by the cleaning medium 62 that flows out of thenozzle row 22, and the cleaning medium 62 can also be reflectedcorrespondingly on the rebound element 18 of the filter elements 14 bythe rebound element 18, and again penetrate through the filter material16 of the filter elements 14. After a predetermined time span, therotation of the filter element 14 is then stopped, and the valve V3 andthe valve V4 are closed. Then the device 10 is again available forcleaning a medium 58 to be cleaned. Optionally one can, before feedingthe medium 58 to be cleaned (see FIG. 13), reapply preliminary cleaningmedium, particularly gaseous or liquid, according to FIG. 14, todisplace residues of the cleaning medium 62 from the device 10. The workprocedure of the device according to the invention that is describedabove in reference to FIGS. 13-15 and to the description, is thencontinued in a new cycle.

By means of the filtering device according to the invention, the filterelement according to the invention, and the method according to theinvention, an effective filtration of the cleaning medium is achieved,regardless of whether it is liquid and/or gaseous, as well as aneffective cleaning by providing rebound elements.

It is claimed:
 1. A method for removing a filter cake, said methodcomprising the steps of: providing a filtering device having a housingthat defines a filtration flowpath through which a filtrate flows, thehousing having at least one inlet and at least one outlet, the filtercake being deposited on at least one cylindrical filter element disposedwithin the filtering device, the at least one cylindrical filter elementcomprises at least one filter material and at least one rebound element,the at least one rebound element having a first flange extending from ahead region and a second flange extending from a foot region, the atleast one rebound element having a structured surface with at least tworecesses mutually parallel in the longitudinal direction of the at leastone rebound element, the at least two recesses are formed extendingbetween the first flange and the second flange, the at least one reboundelement having at least one opening through which the filtrate flowsinto an interior of the at least one rebound element, the at least oneopening is arranged on the structured surface of the at least onerebound element adjacent one of the head region and the foot region inan area of extension of at least one of the at least two recesses, theat least one filter material partially covers the at least one reboundelement, the at least one filter material is a yarn which consists ofone or more individual filaments, and including at least two layers,providing a cleaning device having at least one nozzle, and directing acleaning medium, through the at least one nozzle of the cleaning device,perpendicularly or angularly in relation to the structured surface ofthe at least one rebound element on the at least one cylindrical filterelement, the cleaning medium penetrates through the at least one filtermaterial, rebounds at least partially on the at least one reboundelement, and the filter cake is removed at least partially during therenewed passage through the at least one filter material, wherein the atleast one cylindrical filter element is moved within the filteringdevice while the cleaning medium is directed through the at least onenozzle.
 2. The method according to claim 1, wherein the cleaning deviceis moved during the release of the cleaning medium.
 3. The methodaccording to claim 1, wherein the cleaning medium is at least one of aliquid cleaning medium and a gaseous cleaning medium.
 4. The methodaccording to claim 1, wherein before feeding the cleaning medium, theremaining medium to be cleaned that is present in the housing of thefiltering device is rinsed out by means of a preliminary cleaningmedium.
 5. The method according to claim 1, wherein after the cleaningprocess, the remaining soiled medium that has been left over from thecleaning process and is present in the housing of the filtering device,is rinsed out by means of a post cleaning medium.
 6. The methodaccording to claim 1, wherein the cleaning medium includes at least oneof a gas and a gas mixture.
 7. The method according to claim 1, whereinthe cleaning medium is applied through the at least one nozzle at apressure of at least approximately 3 bar.
 8. The method according toclaim 1, wherein the cleaning medium is fed parallel to a windingdirection of the yarn.
 9. The method according to claim 1, wherein atleast one of the rebounding of the cleaning medium off of the at leastone rebound element and an outflow of the cleaning medium through the atleast one rebound element is increased by the structured surface of theat least one rebound element.